The platinum catalyst features low reactivity (hard to participate in reaction) and high catalytic efficiency. The platinum catalyst has been extensively in many fields, especially the field of fuel cells. In principle, a fuel cell converts chemical energy into electric energy. The high catalytic efficiency of the platinum catalyst can promote the energy conversion efficiency of fuel cells and the productivity of electricity. However, the platinum catalyst is normally made from precious metals and very expensive. Thus, a carbon material doped with nitrogen atoms was developed to replace the platinum catalyst.
As to carbon materials doped with nitrogen atoms, a U.S. Pat. No. 8,221,937 disclosed a “Carbon Nanotube Catalyst Applied to Fuel Cells”, wherein the cathode of a fuel cell comprises a cathode, a connection layer and a catalyst layer; the connection layer is connected with the cathode and includes a conductive polymeric material and a plurality first carbon nanotubes arranged non-parallel; the catalyst layer is connected with the connection layer and includes a plurality of second carbon nanotubes doped with nitrogen atoms and arranged vertically. The second carbon nanotubes doped with nitrogen atoms has a catalytic effect and can promote the power generation efficiency of the fuel cell.
However, carbon nanotubes are likely to agglomerate into carbon nanotube bundles, which have smaller effective area and lower catalytic ability.